With the constant emergence of new technologies, the 3rd Generation Partnership Project (3GPP) needs to consider the continuous evolution and enhancement from a radio interface to a core network in the system architecture evolution in the future mobile communication field, so as to keep its first-mover technical advantage in the mobile communication field within the next 10 years and provide a satisfactory support for the growing demands of operators and users. Therefore, the evolution project EPS (Evolved Packet System) for an all-IP packet switched core network is initiated against such background. The EPS aims to “formulate a portable 3GPP system architecture structure characterized by high data rate, low delay, data packetization and supporting multiple radio access technologies”.
The EPS network is characterized by supporting end-to-end Quality of Service (QoS) assurance, comprehensive packetization, supporting multiple access technologies and real-time services, network layer flattening and the like. FIG. 1 shows a reference architecture of the EPS network; as shown in the FIG. 1, the EPS network further realizes the data separation between a control panel and a user panel, and additionally provides a network element MME (Mobility Management Entity) which serves as a network functional entity for bearing user data of a control panel, and has the functions of supporting roaming, authentication, bearing management and the like. The S6a interface between an MME and a Home Subscriber Server (HSS) provides the download of user data and authentication data, and the like. A UE is accessed to the EPS network through an Evolved Universal Terrestrial Radio Access Network (E-UTRAN), and implements the network registration in the HSS through the MME and acquires the address of a serving gateway and the address of a Packet Data Network (PDN) gateway, so as to be accessed to an operator Internet Protocol (IP) service network through the PDN gateway. The policy control of the EPS network is downloaded to the PDN gateway through a policy control rule function, and related QoS control is performed by the PDN gateway.
The EPS network supports the UE to be accessed thereto through a Serving GPRS Support Node (SGSN, which is a network element in charge of the mobility management at a core network side) by means of a traditional accessing way, such as a Universal Terrestrial RADIO Access Network (UTRAN) or a GSM EDGE Radio Access Network (GERAN), and defines the S6d interface between the SGSN and the HSS, wherein the S6d interface has the same basic function as the S6a interface, is used for downloading the EPS subscription data and GPRS subscription data, and implements the network registration of a user through the SGSN.
The HSS supports that the UE can be registered in a core network through the MME or SGSN, and the HSS stores the addresses of the registered MME and SGSN. The MME or SGSN deletes the stored subscription information of the UE and initiates to the HSS a purge flow of the UE when detecting that the UE is inactive for a long time in the access network served by the MME or SGSN. FIG. 2 shows a register and purge flow of a UE through different access networks in the prior art, in which it is assumed that the registered network nodes MME and SGSN are deployed independently, the flow includes the following steps:
S201˜S204: a UE is initially accessed to an EPS network through E-UTRAN, MME initiates to the HSS an update location flow, and the HSS stores the address of the MME where the UE has been registered;
S205˜S208: the UE is switched and accessed to the EPS network through UTRNA/GERAN, the SGSN initiates to the HSS an update location flow, and the HSS stores the address of the SGSN where the UE has been registered;
S209˜S211: the MME initiates to the HSS a purge flow of the UE when detecting that the UE is inactive for a long time in the E-UTRAN access network served by the MME, the HSS determines whether the source address in a request message is matched with one of all the registered network addresses, and makes the UE purged from the MME and performs related purge operation of the UE when finding that the source address is matched with the address of the MME; and
S212˜S214: the SGSN initiates to the HSS a purge flow of the UE when detecting that the UE is inactive for a long time in the UTRAN/GERAN access network served by the SGSN, the HSS determines whether the source address in the request message is matched with one of all the registered network addresses, and makes the UE purged from the SGSN and performs related purge operation of the UE when finding that the source address is matched with the address of the SGSN.
Furthermore, when deploying a network, an operator may integratively deploy the MME and SGSN and use the same network node or different network nodes. FIG. 3 shows a register and purge flow of a UE through different access networks in the prior art, in which it is assumed that the registered network nodes MME and SGSN are integratively deployed and have the different address in the combined node, the flow includes the following steps:
S301˜S304: a UE is initially accessed to an EPS network through an E-UTRAN, the combined node initiates an update location flow to the HSS through the S6a interface, wherein the source address is the address of MME in the combined node, and the HSS stores the address of MME in the combined node where the UE has been registered;
S306˜S308: the UE is switched and accessed to the EPS network through UTRAN/GERAN, the combined node initiates an update location flow to the HSS through the S6d interface, wherein the source address is the address of SGSN in the combined node, and the HSS stores the address of SGSN in the combined node where the UE has been registered; and
S309˜S311: the combined node initiates to the HSS a purge flow of the UE through the S6a interface when detecting that the UE is inactive for a long time in the E-UTRAN access network served by the combined node, the HSS determines whether the source address in the request message is matched with one of all the registered network addresses, and makes the UE purged from the MME and performs related purge operation of the UE when finding that the source address is matched with the address of the MME.
FIG. 4 shows a register and purge flow of a UE through different access networks in the prior art, in which it is assumed the registered network nodes MME and SGSN are integratively deployed and have the same address in the combined node, the flow includes the following steps:
S401˜S404: UE is initially accessed to an EPS network through an E-UTRAN, the combined node initiates an update location flow to the HSS through the S6a interface, wherein the source address is the address of MME in the combined node, and the HSS stores the address of MME in the combined node where the UE has been registered;
S406˜S408: the UE is switched and accessed to the EPS network through UTRAN/GERAN, the combined node initiates an update location flow to the HSS through the S6d interface, wherein the source address is the address of SGSN in the combined node, and the HSS stores the address of SGSN in the combined node where the UE has been registered; and
S409˜S411: the combined node initiates to the HSS a purge flow of the UE through the S6a interface when detecting that the UE is inactive for a long time in the E-UTRAN access network served by the combined node, the HSS determines whether the source address in the request message is matched with one of all the registered network addresses, since the MME and SGSN in the registered combined nodes have the same address, the source address is matched with both the address of MME and that of SGSN, therefore the HSS makes the UE purged from both the MME and the SGSN and performs related purge operation of the UE.
It can be seen from the abovementioned flow, when receiving a purge UE request from a network node, the HSS will determines whether the source address in the request message is matched with one of all the registered network addresses, and makes the UE purged from a certain network entity, such as the MME or the SGSN, when the source address is matched with the address of the certain network entity. Such matching way does not cause mutual interference when the MME node and the SGSN node have different addresses, i.e., the purge flow of the UE in the MME node does not affect the registration state of the UE in the SGSN node stored by the HSS, or the purge flow of the UE in the SGSN node does not affect the registration state of the UE in the MME node stored by the HSS. However, when the MME node and the SGSN node are integratively deployed and have the same address, such matching way will cause the registration state of the UE in the MME node and the registration state of the UE in the SGSN node, which are stored by the HSS, to be purged during the purge flow of the UE initiated by a combined node.
Obviously, such processing way is improper; in the application scenario of the FIG. 4, the purge flow of the UE initiated by the combined node may cause the problem that the registration state of the UE in the MME or SGSN is registered but the HSS wrongly sets the UE purged.